Metallic aluminium was not produced by mankind until around 200 years ago - but this appears manufactured making the object a baffling find

A piece of aluminium that looks as if it was handmade is being hailed as 250,000-year-old proof that aliens once visited Earth.

Metallic aluminium was not really produced by mankind until around 200 years ago, so the discovery of the large chunk that could be up to 250,000 years old is being held as a sensational find.

The details of the discovery were never made public at the time because it was pulled out of the earth in communist Romania in 1973.

Builders working on the shores of the Mures River not far from the central Romanian town of Aiud found three objects 10 metres (33 feet) under the ground.

It was quickly determined that the two large bones belonged to a large extinct mammal that died 10,000-80,000 years ago, but experts were stunned to find out that the third object was a piece of very lightweight metal, and appeared to have been manufactured.

According to tests, the object is made of 12 metals, 90% aluminium, and it was dated by Romanian officials as being 250,000 years old. The initial results were later confirmed by a lab in Lausanne, Switzerland.

What puzzled experts is that the piece of metal has concavities that make it look as if it was manufactured as part of a more complex mechanical system.